Absorber type refrigerating system with boiler feed



July 12, 1938. BRACE 2,123,708

ABSORBER TYPE REFRIGERATI NG SYSTEM WITH BOILER FEED Filed May'23, 1935 2 Sheets-Shet 1 I HUI Kemper P Brace INVENTOR.

BY ATTORN s.

K. P. BRACE 2,123,703

ABSORBER TYPE BEFRIGERATING SYSTEM WITH BOILER FEED July 12, 1 93s.

2 Sheets-Sheet 2 Kemper' F? Brace INVENTOR.

ATTORNEYS.

Patented July 12, 1938 UNITED STATES PATENT OFFICE Kemper P. Brace, Brooklyn, ,N. Y.

Application May 23,

8 Claims.

This invention relates to refrigerating systems of the absorber type. Its object is to provide a new and simple method of causing circulation of the absorbing liquid from the absorber to the generator or boiler with a minimum of simple moving parts, and without the use of an inert gas or vapor to balance pressures between the absorber and the generator.

Further objects and advantages will become apparent from a study of the description and the drawings.

Referring to the accompanying drawings which are made a part hereof and on which like numerals refer to the same part thruout,

Figure 1 is a view in elevation of one form of the system, and,"

Figure 2 is a similar view of a modification of the system.

Referring to Figure l, numerals 2 and 3 denote the evaporator, the absorber and the generator or boiler, respectively, of an absorber type refrigerating system. The boiler is partially filled with a suitable solution 4 from which refrigerant is boiled ofi by means of another fluid at a higher temperature than the solution 4, as will later be described. The refrigerant used may be ammonia (NI-l3) and the solution 4 may be a solution of ammonium thiocyanate (NHiCHS) in ammonia. Ammonia vapors boiled oil the solution 4 pass liquefied and pass to receiver 8. A fioat controlled valve 9 controls passage of liquid from the receiver to the evaporator and prevents the passage of gas from the receiver to the evaporator in the event that there should be no liquid in the receiver. Heat is extracted from the media being refrigerated which may surround the evaporator, this heat passing into the refrigerant and causing evaporation of some of the refrigerant. The evaporated refrigerant passes thru a pipe l0 into the solution H in the absorber. The solution in the absorber is cooled by a cooler |2, which as here shown may be an air cooler or may be any other suitable cooler. Solution is returned from the absorber 2 to the boiler thru pipe I 3, check valve l4, pipe |5, check valve l6 and pipe Solution is supplied from the boiler to the absorber thru float controlled valve I8, heat exchanger l9 and pipe 20.

The pressure in the boiler is greater than the pressure in the absorber. In order to have a flow of the solution from the absorber tothe boiler systems of this general character heretofore have used an inert gas such as hydrogen to balance the pressure difference between the abthru pipe 5 to a condenser where they are 1935, Serial No. 23,097

sorber and the generator. My system avoids the use of such a gas and provides means for effecting the return of the solution from the absorber to the 'boiler, which means will now be'described. in connection with the means for-heating the boiler 3 with which it is connected.

, An auxiliary boiler2| containsa solution or liquid' 22 which boils at a temperature much higher than the boiling temperature of the solution 4. Suitable examples of such liquids are diphenyl, mercury, benzol chloride, benzyl benzoate, glycerine, and variousoils, etc. The boiler is heated by a suitable heater 23. A pipe 25 conducts the vapor 24 which is boiled off the liquid 22 to a chamber 26 which surrounds a portion of the boiler 3 or which is arranged at least so that the vapors 24 are brought into heat exchange relation with the boiler 3. The boiler 3 being cooler than the boiling point of the liquid 22 will condense the vapor 24, the liquid resulting therefrom falling into a well 21. Heat extracted from the vapors 24 and hot liquid condensed will pass into the solution 4 and effect vaporization of some of this solution, driving off refrigerant, which as stated, may be ammonia. A tube 28 siphons hot liquid from the well 2'! and delivers it into chambers 29 and 30 from which it fiows thru pipe 3| back to the boiler. The pipe 3| has a restricted portion 32 to retard the fiow of liquid from the chambers 29 and 30, for a purpose which will presently appear.

A tube 33 is connected at its upper end with the pipe l5 and extends down into the chamber 29. The 'tube has on its lower end a bulb 34 havber 26 contacts the boiler 3 and boils the solution 4 therein. The boiling point of the solution 4 being lower than the boiling point of the liquid'22, vapors 24 are condensed and collect in the well 21. The hot liquid collecting in the well is still hotter than the boiling point of the solution 4. This hot liquid is siphoned into chambers 29 and'30, and due to the restriction 32 is held in the chambers 29 and 30 for some appreciable time. This heats the solution in the bulb 34 and vaporizes some of it. The resulting pressure forces solution thru pipe I5, check valve l6 and pipe I! into boiler 3.

The check valve i4 prevents the solution from returning to the absorber. As soon as all the liquid in chambers 29 and 30 has drained into the boiler 2|, air will pass down thru chamber 30 and up thru chamber 29 cooling the bulb 34. This will condense the vapors in the bulb 34, reducing the pressure therein to draw solution thru check valve M from the absorber, check valve l5 preventing solution from returning from the boiler. In thisway solution will be pumpedfrom the absorber to the boiler. While the bulb 34 was filling with solution from the absorber, the well 21 was again filling with liquid condensed by the boiler 3 to start the cycle over again.

It is possible that some trouble may be caused by crystallization of NHlCHS in bulb 34 due to the fact the fresh solution from the absorber may not diffuse and mix rapidly in the bulb. To avoid difiiculties of this kind I have provided a modifiedform of the invention which is shown-in Figure 2.

The upper portion of Figure 2 is the same as that shown in Figure 1 and indicates an absorber refrigerating system of conventional construction. Boiler 40 is heated by vapors. boiled off the liquid in the boiler 4| by heater .42. Liquid resulting from contact of the vapors with the walls of the boiler 4|) will collect inwell 43 and flow thru siphon tube 44 to the U-shaped chamber 45 and out of this chamber thru tube 45 back into the boiler 4|. The tube 46 has a restriction 41 to retard flow of the hot liquid from the chamber 45 to the boiler. A second U-shaped chamber. 49 is partially filled with a liquid different from the solution in the boiler and absorber. A metal element 52 carries a cup 53 positioned within the closed end of the U-shaped member 49. The metal element extends into the U- shaped chamber 45 and has fins 54 to effect better heat transfer between the liquid in the chamber and the metal element.

- Operation is as follows: hot liquid returning from the well 43 is held in the chamber 45 long enough for the-heat from the liquid to be transmitted thru the metal element 52 to the cup 53. Some vapor will be generated above the liquid 48 to create a pressure which will act thru the column of liquid to force. a portion of the solution from the absorber thru the check valve 5| into the boiler 40. When all of the liquid has drained out of the chamber 45 air will flow thru the chamber and out thru the upper end, and coming in contact with the end of the element 52 will cool this elementand consequently con-,

dense the vapor above the liquid 48. Reduction of pressure resulting, solution will be drawn from the absorber thru check valve 50, check valve 5| preventing return of solution from the boiler.

For efficient operation the amount of liquid in bulb 34 in Figure 1 and in cup 53 in Figure 2 should be small, so that a large amount of liquid will not have to be heated and cooled. It will be apparent that the liquid in the cup 53 and in the tube 34 will be alternately heated to its boiling point and cooled to the condensing point. The

boiling point will be slightly higher than the boiling point in the refrigerant boiler and the condensing point will be approximately equal to the temperature maintained in the absorber. Since quite a high temperature difference exists between the absorber and the generator it is obviously advantageous to keep the amount of liquid in cup 53 and bulb 34 as small as possible to reduce heat losses due to alternate heating and cooling as it is only the actual'vaporization of the liquids in 53 and 34 that pumps solution from the absorber to the'boiler; The ideal set up would be to have cup 53 or bulb 34 hold only that amount 'of liquid which when entirely vaporized would force the required quantity of weak solution into the boiler at each siphoning of hot liquid from the well.

For controlling the temperature at the evaporator for faster freezing, etc., the simplest and most eflicient way is to design the whole machine large enough to take care of the lowest temperature in the evaporator under the worst conditions and apply a high and low control of the 300 B. t. u. per hour. Then the whole machine should be designed for say 400 B. t. u. per hour at the above evaporator temperature and highest condenser temperature. A thermostat would then be set in the evaporator which would practically shut off the flame under the boiler when the temperature of 10 degrees is reached and turn it on when a temperature of 12 degrees has been attained. Thus the machine would operateabout three fourths of the time at substantially full capacity. If a temperature of 15 degrees is desired in the evaporator, the thermostat could be set to practically shut off the flame at 15 degrees and turn it on at 1'7 degrees and of course .at

this setting the machine could still operate at its full capacity while running but wouldnot run as much of the time as at the lower temperature. It will be obvious to those skilled in the art that various changes-may be made in the invention without departing from the spirit thereof.

I, therefore, do not limit myself to the invention as shown in the drawings and described in the specification but only as set forth in the appended claims.

What I claim is:

1. A refrigerating system of the absorber type comprising a boiler, a condenser, an evaporator, an absorber, an auxiliary boiler, means for continuously driving off vapor from said auxiliary boiler to heat-said first named boiler, means for condensing said vapor and returning it intermittently to said auxiliary boiler, and means for utilizing some of the heat energy in said retuming fluid for effecting transfer of fluid from said absorber to said boiler.

2. In an absorber type'of refrigerating system, a boiler, means for heating the boiler, anevaporator, and an absorber, means for transferring fluid from the absorber to the boiler comprising a fluid line from said absorber to said boiler having spaced apart check valves therein arranged to permit flow of fluid from the absorber to the boiler and prevent reverse flow and a pulsating column of liquid connected in said line between said check valves and means for eiTect-' ing pulsations of said liquid, said last named means being operated by said boiler heating means.

3. A refrigerating system comprising a boiie a fluid heater for said boiler, an evaporator, an absorber, a supply line between said absorber and said boiler, check valves in said line to permit boiler the fluid boiled oil, a conduit for returning solution from 'said absorber to said first named boiler, said conduit having check valves therein to limit flow in one direction only, a connection to said conduit between said valves, a bulb in said connection, said bulb being placed in the path of the fluid returning to the said auxiliary boiler whereby the fluid therein is heated to subject the solution in said conduit to a pressure to forcesaidsolution into the said first named boiler.

5. A refrigerating system of the absorber type comprising a boiler, a condenser, an evaporator and absorber and a liquid return line from the absorber to the boiler, an auxiliary boiler having a connection for conducting vapor boiled off from said auxiliary boiler into contact with the first named boiler to condense said vapor and heat said boiler, a reservoir for collecting the con,- densate, a siphon for intermittently returning liquid from said reservoir to said auxiliary boiler, and means for utilizing heat extracted from said returning liquid for forcing liquid thru said liquid return line from the absorber to the first named boiler.

6. A refrigerating system of the absorber type comprising a boiler, a condenser, an evaporator and absorber, a liquid return line from the absorber to the boiler, an auxiliary boiler, means for heating said first named boiler by vapors boiled off from said auxiliary boiler, a pump having a reciprocating liquid piston, said pump having its suction and'discharge communicating by said auxiliary boiler for reciprocating said piston. 4

7. A refrigerating system of the absorber type comprising a boiler, a condenser, an evaporator and absorber, a liquid return line from the absorber to the boiler, an auxiliary boiler, means for boiling off vapor from said auxiliary boiler and bringing it into contact with the first named boiler toheat said first named boiler, a line for returning liquid condensed from said vapor to the auxiliary boiler, areservoir in said last named line, a restriction in said last named line intermediate theauxiliary boiler and said reservoir to hold liquid in said reservoir for a predetermined time, a liquid piston pump communicating with the liquid return line, and means operated by heat extracted from the fluid returning to the auxiliary. boiler for operating said piston to force liquid from the absorber to the boiler. 1

8. In an absorber type of refrigerator, a boiler, means -for heating said boiler, an evaporator, an absorber, aconduit for the return of liquid from said absorber to said boiler and means for 'eflecting the flow of liquid through said conduit comprising a pulsating column of liquid for intermittently transferring energy to the liquid in said conduit and means for utilizing said boiler heating means for effecting pulsation of said column of liquid.

KEMPER P. BRACE.

i with said liquid return line, and means operated 

